Is there a standard set of benchmark files to compare Blender installations?
The benchmarking file often used is the 'BMW Benchmark' file by Mike Pan, available on the blender.org site under 'demo files':

https://www.blender.org/download/demo-files/

There are other files on that page which are sometimes used by developers to test Cycles improvements, called 'Production benchmark'. 

If you then want to compare your 'BMW Benchmark' results with other blender users you can use the 'Blender Cycles Benchmark' spreadsheet:

The Blender Artist's thread for that spreadsheet is here, just in case the link gets changed at some point.